ON THE PRINCIPLES OF ANTISEPTIC SURGERY 345 



antiseptic lotion and spread widely round the field of operation are an important 

 aid in this respect. 



The foregoing considerations indicate that the troublesome complication of 

 irrigating during stitching may be safely omitted. 



The operation being concluded, an external dressing such as shall effectually 

 prevent the access of septic mischief till healing is accomplished is, of course, 

 a matter of essential importance. For this purpose some surgeons have of late 

 years employed materials merely aseptic, such as cotton wadding sterilized by 

 heat. But such a dressing having nothing in it to counteract any accidental 

 defilement, must demand an almost impossible degree of care in its manipulation 

 in order to ensure that it is truly aseptic as left upon the patient. The mere 

 aseptic dressing has also the fatal defect that it is liable to be occasionally soaked 

 to the surface with discharge, in which septic development will then be free 

 to spread inwards to the w^ound. I believe, therefore, that a dressing, in order 

 to be trustworthy, must be charged with some chemical antiseptic substance. 

 Idealty this substance ought to possess three qualifications ; it should be 

 thoroughly reliable in its antiseptic action, it should be capable of being stored 

 up in the material charged with it so that it cannot be washed away by the dis- 

 charge before the dressing is renewed, and it should be free from irritating proper- 

 ties, so as not to interfere with healing. The nearest approach to this ideal which 

 I have yet met with is presented by a combination of cyanide of mercury with 

 cyanide of zinc. Chemists are not agreed as to whether the two constituents 

 are united in true chemical combination. But however this mav be, their 

 association is so intimate that, whereas the cyanide of mercury alone is freely 

 soluble in water and serum and highly irritating to the skin, the combination 

 'is almost absolutely insoluble in water and requires about 3,000 parts of serum 

 to dissolve it at the temperature of the human body. Hence, if diffused in 

 a dressing, it remains most efhciently stored in spite of very free discharge ; while 

 it is so slightly irritating as not to interfere materially with healing, requiring 

 no protective layer to be interposed between it and the wound. As regards 

 its antiseptic virtues, it is very remarkable for inhibitory efticac}', i.e. for the 

 power of preventing the development of microbes in its vicinity, even in the 

 liquid which tests more severely than any other the antiseptic properties of 

 mercurial compounds, viz. the mixture of serum and blood corpuscles which 

 constitutes the first and most copious discharge from a wound. It is, how- 

 ever, very feeble as a germicide : and in order to make sure that a dressing 

 containing it shall have no hurtful organism alive in it when it is applied. 

 it is well to damp the dressing with a germicidal lotion before applying it. 

 For this purpose a i to 20 carbohc solution seems tlie best that can be em- 



LISTER II A a 



